1. The Field of the Invention
This invention relates to navigation systems, and, more particularly, to relative-position navigation systems measuring distance and direction according to movement of a sensor.
2. The Background Art
The Global Positioning System (GPS) is the most common navigation system in use today. As known in the art, GPS relies on receiving signals from orbiting satellites to determine the position of a GPS receiver. This system has been very reliable and accurate and has therefore found many civilian and military applications.
However, there are situations where GPS is not operable. For example, GPS jammers can render GPS receivers useless. Likewise, within buildings, particularly fortified structures, signals may not be receivable. Within caves and underwater, GPS signals likewise cannot be received.
An alternative method, for position sensing is to use accelerometers as the basis for a Relative Positioning System (RPS). The acceleration outputs from the accelerometers can be integrated twice to determine a change in position. In general, accelerometers can be adequate. However, the accelerometers themselves may be sophisticated micro-electromechanical structures and can be expensive. The control circuits needed to interface with the accelerometers may also be subject to natural and man-made interference phenomena. It would be an advance in the art to provide an alternative relative positioning detection system.
The apparatus and methods disclosed herein provide a low cost and robust Velocimeter as a distance and direction determinant as an alternative to existing absolute positioning system or navigation systems.